The present invention relates to a photocatalyst nanomaterial comprising a solid substrate and a metal oxide/oxyhydroxide arranged on the solid substrate forming a coating having a thickness comprised between 1 nm and 1 micrometer and having an amorphous structure. The invention also relates to a nanometric coating which comprises the described photocatalyst material and metallic nanoparticles, as well as to the method for obtaining the catalyst material, to the use of the catalyst material as a photocatalyst in the ultrafast synthesis of metallic nanoparticles, and to the use of the nanometric coating in the manufacture of optical sensors, biocidal coatings and elimination of reactive oxygen species.